I got the Madmen box sets as they came out. I started watching Headmasters but got maybe 10 or 12 episodes in before I just took the DVD out and never went back. I think the problem with the series was that it was too close in appearance to the US series. The animation I think suffered by trying to emulate the US series, and having unfamiliar voices of familiar characters (in a foreign language) and music made it quite jarring to watch.

Masterforce on the other hand I loved and it's because the characters were all new (although Ginrai's transtector sure looked familiar), the animation was more anime and the story was a lot more solid and interesting. I liked that the series started being about Transformers pretending to be humans, and transitioned to being about humans who "became" Transformers. It's a very different take but I could see it being off putting to people who want to watch a show about Transformers not humans. Worked for me though and I would recommend giving it a go over the other three core series.

I watched the first episode of Victory and haven't gone back yet. I'll get to it, but the opening episode really didn't sell me on the series.